System And Method For Acquiring Images From An Aerial Vehicle For 2D/3D Digital Model Generation

ABSTRACT

A method for capturing images of large target area using a single camera configured with an aerial vehicle (AV) for reconstructing a high-resolution image is disclosed including the steps of moving the AV over the area of interest along a straight path; capturing a first set of images of an area down below by pointing an optical axis of the camera towards a first side of the straight path such that the optical axis makes a first predefined angle with vertical; and capturing a second set of images of the area down below by pointing the optical axis of the camera towards a second side of the straight path such that the optical axis makes a second predefined angle with respect to the vertical. Side overlap between the first and second set of images is optimized to account for error in camera movement.

RELATED APPLICATION(S)

This application is a continuation-in-part of U.S. application Ser. No. 16/768,244, filed May 29, 2020, which is the U.S. National Stage of International Application No. PCT/IB2018/059512, filed Nov. 30, 2018, which designates the U.S., published in English, and claims priority under 35 U.S.C. § 119 or 365(c) to Indian Application No. 201721043086, filed Nov. 30, 2017. The entire teachings of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to field of image optics. In particular, the present disclosure pertains to a system and method for acquiring images from an aerial vehicle for 2D/3D digital model reconstruction.

BACKGROUND

Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

In aerial imaging, unmanned aerial vehicles (UAV) are equipped with cameras to capture images of an area for mapping. Cameras have a fixed field of view and based on the field of view of camera, lens, resolutions, frontal and side overlap requirement and altitude, the ground area captured in a single photo is limited. This in turn increases the time spent by the UAV on the area for image capturing to make a detailed area map. Wide-angled field of view cameras can be used with UAVs for fast area mapping but they are generally low resolution with lesser pixels per image, leading to grainy and blurred images. Even though the wide-angled approach would provide a larger field of view in one shot, the associated image quality deterioration is undesirable.

In order to overcome this problem, many prior-art techniques make use of an aerial camera system with more than one camera of which each camera is directed towards a unique area on the ground to provide a large field of view in which the captured images are then overlapped. But such techniques also increase the payload weight of the UAV in turn reducing the UAV flight.

Prior art references have dealt with problem of capturing images of land mass over large areas. For example, U.S. Pat. No. 8,687,062B1 discloses an aerial camera system comprising: a camera cluster, including a plurality of cameras, each camera orientated in a direction selected from a plurality of different directions. It further incorporates one or more rotators that rotate the camera cluster about respective one or more axes in response to one or more signals from a control module. The cited reference also discloses a method of controlling the disclosed camera cluster to capture images, which involves rotation of the camera cluster about a vertical axis (i.e. pan axis) and a horizontal axis. The disclosed camera system and method of capturing images requires a plurality of cameras increasing the weight of the camera system which is not a feasible solution for an aerial platform like UAV.

Therefore, there is a need in the art to present a method that not only provides better resolution and field of view for imaging applications during the flight path of the UAV but also provides optimum overlapping of captured images to ensure maximum coverage of the ground area and capturing the same in the resultant stitched image for high quality image construction with a single camera.

All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.

Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

OBJECTS OF THE PRESENT DISCLOSURE

It is an object of the preset disclosure to provide an economical and simple to implement method for acquiring high-resolution images of large target area from an aerial platform.

It is another object of the preset disclosure to provide a system and method for acquiring images of large target area with a single camera by moving the camera along the flight path adapted to cover the entire area of interest.

It is another object of the present disclosure to provide an economical and simple to implement method for acquiring high-resolution images of large target area from an aerial platform with a single camera.

It is another object of the present disclosure to provide a system and method for capturing images along an axis perpendicular to the flight path of the aerial vehicle.

It is another object of the present disclosure to provide a system and method for capturing images that reduce flight time for 2D/3D digital model reconstruction of a large area.

It is an object of the present disclosure to provide a system and method for capturing images that reduce the flight time of the UAV for mapping a large target area.

SUMMARY

The present disclosure relates to field of image optics. In particular, the present disclosure pertains to a system and method for acquiring images from an aerial vehicle for 2D/3D digital model reconstruction.

An aspect of the present disclosure provides a method for acquiring a set of images of a target area using an aerial vehicle for reconstructing an image for a large area of interest using a single camera, the proposed method including the steps of moving the aerial vehicle over the area of interest along a straight path; capturing a first set of images of an area down below by pointing an optical axis of the camera towards a first side of the straight path such that the optical axis makes a first predefined angle with respect to a vertically downward direction of the aerial vehicle; and capturing a second set of images of the area down below by pointing the optical axis of the camera towards a second side of the straight path such that the optical axis makes a second predefined angle with respect to the vertically downward direction. The optical axis of the camera is perpendicular to a direction of motion of the aerial vehicle.

During the steps of capturing the first set of images and the second set of images, the camera is moved alternately to the first side and the second side of the aerial vehicle.

In an aspect, the step of capturing the first set of images and the second set of images is characterized by absence of need of a side overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along the straight path, as the area covered by the first set of images and the second set of images is aligned along the adjacent sides.

In an embodiment, the method can include the step of capturing the first set of images and the second set of images such that the first set of images and the second set of images captured during movement of the aerial vehicle along the straight path include a side overlap.

In an embodiment, the method can include the step of capturing the first set of images and the second set of images such that the side overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths is adequate only to take care of any error in the movement of the camera between the first side and the second side.

The method can further include the step of moving the aerial vehicle over the area of interest in parallel straight paths such that adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two adjacent straight paths have a side overlap.

In application, the side overlap between the adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two of the adjacent straight paths can be more than the overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths.

The method can further include the step of adjusting, using a ground controller, a percentages of the overlap between the adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two of the adjacent straight paths and the overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths.

The first side and the second side can be left side and right side along wingspan direction of the aerial vehicle.

The single camera used for capturing the first set of images and the second set of images can be a high-resolution camera.

An aspect of the disclosure relates to a system for acquiring a set of images of a target area using an aerial vehicle for reconstructing an image for a large area of interest. The disclosed system includes a camera movably configured with the aerial vehicle, and configured to capture, as the aerial vehicle is moving over the area of interest in a straight path, a first set of images of an area down below by pointing an optical axis of the camera towards a first side of the straight path such that the optical axis makes a first predefined angle with respect to a vertically downward direction of the aerial vehicle; and capture a second set of images of the area down below by pointing optical axis of the camera towards a second side of the straight path, such that the optical axis makes a second predefined angle with respect to the vertically downward direction In an aspect the camera is configured with the aerial vehicle such that, during movement of the camera between the first side and the second side, the optical axis of the camera is perpendicular to a direction of motion of the aerial vehicle.

The system can further include a controller configured to control the movement of the aerial vehicle and the camera.

The system can include a rotary device coupled to the camera to tilt the optical axis of the camera between the first side and the second side. The rotary device can be any of a servo motor, a stepper motor, a DC motor and an actuator.

The controller can be operatively coupled to the rotary device to alternately tilt the optical axis of the camera between the first side and the second side during the movement of the aerial vehicle in the straight path such that side overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths is adequate only to take care of any error in the movement of the camera between the first side and the second side.

The controller can be configured to move the aerial vehicle over the area of interest in parallel straight paths such adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two adjacent straight paths have a side overlap which is more than the overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths.

The controller can be configured to allow adjusting a percentage of the overlap between the adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two of the adjacent straight paths and the overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths. The controller can be configured to enable adjustment of the overlap remotely, such as from a ground position, such as using a ground controller.

Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. The diagrams are for illustration only, which thus is not a limitation of the present disclosure.

FIG. 1 illustrates an exemplary block diagram showing processing pipeline of the proposed system for image acquisition, in accordance with an embodiment of the present disclosure.

FIG. 2 illustrates an exemplary flight path in accordance with an embodiment of the present disclosure.

FIG. 3 illustrates an exemplary camera oscillating between positions P1 and P2 in accordance with an embodiment of the present disclosure.

FIG. 4A illustrates a typical image capturing technique where images are captured in nadir position.

FIG. 4B illustrates an image capturing technique using a single camera, in accordance with an embodiment of the present disclosure.

FIGS. 5A through 5C illustrate camera field of view (FOV) while at position P1, P2, and effective FOV of the oscillating camera respectively in accordance with an embodiment of the present disclosure.

FIG. 6 illustrates an exemplary side-view representation of motor and camera mounting in accordance with an embodiment of the present disclosure.

FIG. 7 illustrates a process for acquiring images of a target area using an aerial vehicle in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.

As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

Various terms as used herein as shown below. To the extent a term used in a claim is not defined, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing

Term ‘Aerial Vehicle (AV)’ or ‘Unmanned Aerial Vehicle (UAV)’ as used herein referred to as an aircraft that carries no human pilot or passengers. UAVs—sometimes called “drones”—can be fully or partially autonomous but are more often controlled remotely by a human pilot. Accordingly, for capturing images captured using a camera device mounted on the UAV for reconstruction into a 2D/3D digital model.

Term ‘optical axis’ is a line along which there is some degree of rotational symmetry in an optical system such as a camera lens or microscope. The optical axis is an imaginary line that defines the path along which light propagates through the system, up to first approximation. The camera can be tilted along the plane perpendicular to the flite direction to efficiently capture the images.

Term ‘field of view (FOV)’ as used herein refers to the open observable area that can be captured using the optical device such as camera. In the case of optical devices and sensors, FOV describes the angle through which the devices can pick up electromagnetic radiation.

Embodiments explained herein pertain to a method for capturing images of a large target area of interest using a single high-resolution camera mounted on an aerial platform so that the captured images may be used for reconstructing image of the targeted area. In particular, the proposed method is based on use of a single camera, which makes the image capturing apparatus light and suitable for unmanned aerial vehicles that have low load carrying capacity. More particularly, the disclosed method proposes a scheme for image capturing that reduces total flight time of the aerial vehicle over the area of interest. In an aspect, the disclosed method optimizes a side overlap between the captured images, which results in reduction of flight time of the aerial vehicle, thereby resulting in corresponding cost benefits.

In an exemplary embodiment, the disclosed method includes steps of moving the aerial vehicle along a straight flight path and capturing images using a single camera that is configured to capture images by alternately tilting the camera to two sides about an axis perpendicular to the flight path. The camera can be tilted towards left and right and capturing sets of images during the right tilt and the left tilt. Overlap between the left side images and the right side images is optimized to account for any error in the camera movement.

In another aspect, a system for capturing images of a large target area of interest using a single high-resolution camera mounted on an aerial platform is disclosed that enables implementation of the disclosed system.

FIG. 1 illustrates an exemplary block diagram showing processing pipeline of the proposed system for image acquisition. As shown therein, the image acquisition system requires Ground sample distance (GSD) 102-1, Area of interest 102-2, camera information 102-3, flight goals 102-4, unmanned aerial vehicle autopilot 104-1 and Ground Control Station (GCS) 104-2 for mission planning 108. Further, based on the prepared or generated mission plan 108 image acquisition 110 can be performed. Further, based on the acquired image photogrammetry software 112 can be used for preparing or reconstructing an image of area of interest. Further, attributes such as camera calibration 106-1, Geomorphic Change Detection (GCD) 106-2, and Geotags 106-3 can be used by the photogrammetry software 112 for reconstructing or stitching the acquired image to generate the image of the area of interest 102-2.

FIG. 2 illustrates an exemplary flight path 204 comprising a plurality of parallel tracks (also referred to as straight paths and the two terms used interchangeably hereinafter) of the aerial vehicle over an area of interest 202 (shown as a hatched rectangle). The image acquisition system can control the autopilot 104-1 of the aerial vehicle move in zig-zag manner to make the vehicle travel along the parallel paths so that the area of interest is covered.

In an exemplary embodiment, for a given area of interest (AOI) 202 a flight path for the aerial vehicle (interchangeably referred to as unmanned aerial vehicle (UAV) hereinafter) is to be determined to efficiently cover entire AOI. In an embodiment, a number of tracks/straight paths are determined to enable tracking the complete AOI. The exemplary illustration of FIG. 2 shows 5 tracks. However, it should be noted that number of tracks is inversely proportional to distance between adjacent tracks (w), thus, if distance w between the tracks decreases number of tracks increases, and if the distance w decreases the number of track increases.

It can be easily deduced that if number of tracks decrease then AV travel distance decreases, and if AV travel distance decreases, then the flight time decreases as well. The factors which affect the distance (w) between the tracks include:

-   -   1. side overlap percentage requirement;     -   2. flying altitude or flight height; and     -   3. camera field of view (FOV)

Side Overlap Percentage Requirement:—If the Side Overlap percentage decreases then distance (w) between the tracks increases. But since side overlap percentage is an important requirement for the stitching or reconstructing of the images, and hence there is a limitation on an extent that the side overlapping could be decreased.

Flying Altitude (H):—If flying altitude (H) increases then distance (w) between the tracks increases. But flying altitude (H) is limited by GSD constraint. Further, the altitude H has a limitation since, if altitude is increased various attributes such as clarity etc. are highly reduced thereby affecting quality of the final image.

Camera Field of View (FOV):—For a given camera system, the FOV is fixed.

FIG. 3 illustrates an exemplary camera oscillating between positions P1 and P2 in accordance with an embodiment of the present disclosure.

In a typical UAV image capturing technique, where camera 302, mounted on the UAV, is capturing images in the nadir direction with frontal overlap, assuming constant or given UAV speed,

-   -   Time interval between consecutive images can be Tc     -   Distance between two consecutive images can be Dc.

In an embodiment, the present disclosure provides a method for oscillating camera 302 between positions P1 and P2 on ground below the UAV, and further capturing sets of images at the P1 and P2 positions. For given UAV speed and frontal overlap percentage requirement, we have Tc and Dc.

In an embodiment, proposed method for acquiring large mapping area images by UAV equipped with the camera 302. The camera 302 can be configured to capture images along a single axis (x-axis) perpendicular to the UAV's flight direction (z-axis) to increase the FOV and reduce the travel distance for mapping large areas. The camera 302 can oscillate/swing along the x-axis between 2 positions (left and right) to capture sets of images. The captured sets of images can then be processed through an image stitching set of instructions to get the final area mapping images.

It would be appreciated by the person skilled in the art that capturing of lateral images perpendicular to the flight path enables covering large FOV compared to capturing the images in nadir position, and hence reduces the travel distance for mapping large areas.

In another aspect, capturing images on the right side and the left side as the aerial vehicle is moving along a straight path also does away with any requirement of a side overlap between the two sets (hereinafter also referred to as first set of images and second set of images) of images captured on the left side and the right side as the area covered by the first set of images and the second set of images is aligned along the adjacent sides and the captured images can be stitch perfectly enough.

In an embodiment, there can be an overlap between the two sets of images captured on the left side and the right side, which overlap is optimized to account for any error in camera positioning during its movement to the left side and the right side. The optimized overlap, as discussed earlier, increases distance between adjacent parallel straight paths reducing the total number of straight paths, thereby reducing total flight time for capturing the images of the area of interest.

In this invention, there is only one camera mounted on a UAV which oscillates between 2 positions P1 and P2. The camera first tilts to the position P1 (camera tilted by ∂/2) and a first image is captured, then the camera oscillates/tilts to the position P2 (camera tilted by −∂/2) and a second image is captured and the camera moves back to the position P1 to repeat the process. Thus, a number of images are captured with the camera in position P1 as the aerial vehicle moves along a track/straight path, and these images are collectively referred to as first set of images. Likewise, images captured from position P2 are referred to as second set of images. The first set of images and the second set of images taken will be with the time period (Tc/2) or (Dc/2). The rotation axis of the camera is parallel to the flight direction, whereas the image capturing axis of the camera is perpendicular to the flight direction. Speed of the aerial vehicle and movement of the camera between the positions P1 and P2 can be synchronized such that there is a frontal overlap between consecutively captured images from the any of the two positions P1 and P2.

Image Capturing Sequence:

-   -   a. Move camera to position P1 (at angle ∂/2 from the center)     -   b. Initiate image capture     -   c. Wait till image capture process is complete     -   d. Move camera to position P2 (at angle −∂/2 from the center)     -   e. Repeat step (b) and (c)     -   f. Go to step (a)

Referring to FIGS. 4A and 4B, it is apparent that L2>L1 where, L1=Distance between the left most and right most edges of 2 consecutive images on ground using existing techniques as displayed by FIG. 4A. L2=Distance between the left most and right most edges of 2 consecutive images on ground using current invention as displayed by FIG. 4B

Referring to FIGS. 5A through 5C Field of View (FOV) of a camera is usually defined by angles for the horizontal or vertical component of the FOV. A larger angle translates to a larger field of view, though the resulting image would be highly pixelated. For imaging a large area using a camera with a smaller FOV when at position P1 and P2, and when the camera oscillates between P1 and P2 capturing images, the FOV is combined giving an increased FOV as displayed in FIG. 5C.

Total Effective FOV (EFOV)=FOV+(∂/2+∂/2)

EFOV=FOV+∂(assume ∂<FOV)

Thus, FOV has increased by ∂

Now flight plan can be computed with EFOV in place of FOV. This will increase distance (w) between the tracks and reduce the number of tracks, reducing UAV travel distance for mapping an area.

L=2H tan(FOV/2)

For an example, if FOV=70° and ∂=40°. Therefore, EFOV=FOV+∂=110° and assuming H=100 m

L _(FOV)=2×100×Tan(70°/2)=140 m

L _(EFOV)=2×100×Tan(110°/2)=280 m

In this method, a 60% increase in the FOV increased the distance (w) between the tracks by 100%. It would be appreciated by the person skilled in the art that the by capturing images by the camera while oscillating between positions P1 and P2 a large section of the AOI can be easily covered and hence in turn the travel distance of the UAV can be reduced almost by 40% by utilizing the current technique.

FIG. 6 illustrates an exemplary side-view representation of motor and camera mounting in accordance with an embodiment of the present disclosure.

In an embodiment, the current technique could be implemented using a AV 608. The AV 608 can be used for mounting the various components to facilitate capturing of images by camera 602 being mounted over the AV 608, thereby capturing images of entire large area of interest. The AV 608 can include, but not limiting only to a drone, a spider cam etc. for maneuvering the camera 602 over the large area of interest. The AV 608 can further include an arrangement of a rotary device 604 such as motor operatively coupled to the camera 602 using a shaft 606. The camera 602 is configured such that rotary movement of the rotary device 604 can be configured such that the rotary device can affect the camera 602 to oscillate between positions P1 and P2 (as indicated in FIGS. 5A to 5C). The camera 602 first tilts to the position P1 (camera tilted by ∂/2) and a first set of images are captured, then the camera 602 oscillates/tilts to the position P2 (camera tilted by −∂/2) and a second set of images are captured. The first set of images and the second set of images taken will be with the time period (Tc/2) or (Dc/2). The rotation axis of the camera 602 is parallel to the flight direction, whereas the image capturing axis of the camera 602 is perpendicular to the flight direction of the AV 608.

FIG. 7 illustrates an exemplary flow diagram showing different steps involved in the disclosed method for acquiring images of a target area using an aerial vehicle.

In an aspect, the proposed method may be described in general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, functions, etc., that perform particular functions or implement particular abstract data types. The method can also be practiced in a distributed computing environment where functions are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, computer executable instructions may be located in both local and remote computer storage media, including memory storage devices.

The order in which the method as described is not intended to be construed as a limitation, and any number of the described method blocks may be combined in any order to implement the method or alternate methods. Additionally, individual blocks may be deleted from the method without departing from the spirit and scope of the subject matter described herein. Furthermore, the method may be implemented in any suitable hardware, software, firmware, or combination thereof. However, for ease of explanation, in the embodiments described below, the method may be considered to be implemented in the above described system.

Referring back to FIG. 7, the method 700 can include, as at block 702, moving the aerial vehicle along a straight path. At block 704 of the method 700, a first set of images of an area down below can be captured by pointing an optical axis of the camera, such as camera 302 shown in FIG. 3, towards a first side of the aerial vehicle, such that the optical axis makes a first predefined angle with respect to a vertically downward direction of the aerial vehicle. Further, at block 706, the method 700 can include the step of capturing a second set of images of the area down below by pointing the optical axis of the camera 302 towards second side of the aerial vehicle such that the optical axis makes a second predefined angle with respect to the vertically downward direction. The camera 302 can be configured with the aerial vehicle such that, during movement of the camera between the first side and the second side, an optical axis of the camera is perpendicular to a direction of motion of the aerial vehicle.

The first set of images and the second set of images can be captured by moving the camera alternately to the first side and the second side. The step of capturing the first set of images and the second set of images can be characterized by absence of need of a side overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along the straight path, as the area covered by the first set of images and the second set of images is aligned along the adjacent sides.

The method 700 can further include the step of capturing the first set of images and the second set of images such that side overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths is adequate only to take care of any error in the movement of the camera between the first side and the second side, thereby resulting in an optimized overlap to reduce the flight time of the vehicle as discussed earlier.

The method 700 can further include the step of moving the aerial vehicle over the area of interest in parallel straight paths, such as shown in FIG. 2, such adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two adjacent straight paths have a side overlap. The side overlap between the adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two of the adjacent straight paths is more than the side overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths.

The method 700 can further include the step of adjusting, using a ground control station, such as ground control station 104-2 shown in FIG. 1, a percentages of the side overlap between the adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two of the adjacent straight paths and the overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths.

The first side and the second side can be left side and right side along wingspan direction of the aerial vehicle.

In implementation, the camera 302 can be a high-resolution camera.

While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE PRESENT DISCLOSURE

The present disclosure provides an economical and simple to implement method for acquiring high-resolution images of large target area from an aerial platform.

The present disclosure provides a system method for acquiring images of large target area with a single camera by moving the camera along the flight path adapted to cover the entire area of interest.

The present disclosure provides an economical and simple to implement method for acquiring high-resolution images of large target area from an aerial platform with a single camera.

The present disclosure provides a system and method for capturing images along an axis perpendicular to the flight path of the aerial vehicle.

The present disclosure provides a system and method for capturing images to reduce flight time for 2D/3D digital model reconstruction of a large area.

The present disclosure provides a system and method for capturing images that reduces the flight time of the UAV for mapping a large target area. 

What is claimed:
 1. A method for acquiring a set of images of a target area using an aerial vehicle for 2D/3D digital model reconstruction for a large area of interest using a single camera, said method comprising: moving the aerial vehicle over the area of interest along a straight path; capturing a first set of images of an area down below by pointing an optical axis of the camera towards a first side of the straight path such that the optical axis makes a first predefined angle with respect to a vertically downward direction of the aerial vehicle; and capturing a second set of images of the area down below by pointing the optical axis of the camera towards a second side of the straight path such that the optical axis makes a second predefined angle with respect to the vertically downward direction; wherein the optical axis of the camera is perpendicular to a direction of motion of the aerial vehicle.
 2. The method as claimed in claim 1, wherein the method comprises moving the camera alternately to the first side and the second side.
 3. The method as claimed in claim 1, wherein capturing the first set of images and the second set of images is characterized by absence of need of a side overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along the straight path, as the area covered by the first set of images and the second set of images is aligned along the adjacent sides.
 4. The method as claimed in claim 1, comprising capturing the first set of images and the second set of images such that the first set of images and the second set of images captured during movement of the aerial vehicle along the straight path include a side overlap.
 5. The method as claimed in claim 4, comprising capturing the first set of images and the second set of images such that the side overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths is adequate only to take care of any error in the movement of the camera between the first side and the second side.
 6. The method as claimed in claim 5, wherein the method comprises moving the aerial vehicle over the area of interest in parallel straight paths such adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two adjacent straight paths have a side overlap.
 7. The method as claimed in claim 6, wherein the side overlap between the adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two of the adjacent straight paths is more than the side overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths.
 8. The method as claimed in claim 6, comprising adjusting, using a ground controller, a percentage of the side overlap between the adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two of the adjacent straight paths and the overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths.
 9. The method as claimed in claim 1, wherein the first side and the second side are left side and right side along wingspan direction of the aerial vehicle.
 10. The method as claimed in claim 1, wherein the camera is a high-resolution camera.
 11. A system for acquiring a set of images of a target area using an aerial vehicle for reconstructing an image for a large area of interest, said system comprising: a camera movably configured with the aerial vehicle, said camera is configured to: capture, as the aerial vehicle is moving over the area of interest in a straight path, a first set of images of an area down below by pointing an optical axis of the camera towards a first side of the straight path such that the optical axis makes a first predefined angle with respect to a vertically downward direction of the aerial vehicle; and capture a second set of images of the area down below by pointing optical axis of the camera towards a second side of the straight path, such that the optical axis makes a second predefined angle with respect to the vertically downward direction; wherein the camera is configured with the aerial vehicle such that, during movement of the camera between the first side and the second side, an optical axis of the camera is perpendicular to a direction of motion of the aerial vehicle.
 12. The system as claimed in claim 11, wherein the system comprises a controller configured to control the movement of the aerial vehicle and the camera.
 13. The system as claimed in claim 12, wherein the system comprises a rotary device coupled to the camera to tilt the optical axis of the camera between the first side and the second side.
 14. The system as claimed in claim 13, wherein the rotary device is selected from a group comprising a servo motor, a stepper motor, a DC motor and an actuator.
 15. The system as claimed in claim 13, wherein the controller is operatively coupled to the rotary device, and configured to alternately tilt the optical axis of the camera between the first side and the second side during the movement of the aerial vehicle in the straight path such that side overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths is adequate only to take care of any error in the movement of the camera between the first side and the second side.
 16. The system as claimed in claim 15, wherein the controller is configured to move the aerial vehicle over the area of interest in parallel straight paths such that the adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two adjacent straight paths have a side overlap, which side overlap is more than the overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths.
 17. The system as claimed in claim 16, wherein the controller is configured to allow adjusting a percentages of the overlap between the adjacent first set of images and the second set of images captured during movement of the aerial vehicle along any two of the adjacent straight paths and the overlap between the first set of images and the second set of images captured during movement of the aerial vehicle along any of the straight paths. 